Personally, I would try
$string = strip_tags($string, '<url> </url>');
and get those tags out of there.
Then you are left with your string.
send it out like this:
print("<a href="$string">$string</a>[code]
or create another variable for a "friendly" name for the url.
I don't have a machine here to test it on, but I am guessing this will work.